The reason for the pink color of the leucorrhoea: 1. It may be caused by endometrial polyps or submucosal fibroids. This may be due to endometrial polyp or submucosal fibroid, which may be diagnosed by gynecologic ultrasound and treated by hysteroscopy if necessary. 2. If the patient has an intrauterine device, this may also occur if the ring has moved down.